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15.3.6.2 Bounds and Constraints

Bounds and Constraints can restrict the parameter values to a specific range, and avoid the parameters wandering into wrong parameter regions. For example, in the exponential growth model:

y=Aexp[(x-x_0)/t]\,\!

A value of the parameter t close to zero may cause instabilities. A constraint such as t ≥ 0.1 may prevent the problem.

Parameter Bounds include lower (LB) and upper bounds (UB), both of which can be set directly in the Bounds tab of the NLFit dialog:
Bounds nlsf small.png

Constraints enable you to set linear constraints for the parameters. You can set these constraints in the Constraints box in the Code tab of the NLFit dialog:
Constraints nlsf small.png

 

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